Review paperApplied neurophysiology of the horse; implications for training, husbandry and welfare
Introduction
Much is known about the behaviour of horses as a result of an increasing body of applied research. This greatly improves our ability to keep and train the horse in optimal ways. Understanding the neural circuits underlying equine behaviour has the potential to further optimise these strategies of husbandry and training. The aim of this review is to present general and equine-specific neurophysiological information within a translational framework, and by doing so, enhance the knowledge base of equitation science from a practical perspective. Two main areas of neurophysiological evidence will be discussed. The first relates to mechanisms of learning and motivation and thus the training of the horse. The second concerns the identification of the equine neurophysiological phenotype, through behavioural and genetic probes, as a way of improving strategies of equine husbandry and training. The review concludes with a discussion on areas of future research focusing on how neurophysiological systems can potentially be modulated, in a way that is both beneficial to horse (welfare) and rider (performance). In addition, the issue of performance versus welfare will be addressed throughout the review, with an emphasis on how added neurophysiological insight has the potential to help improve performance without diminishing welfare and vice versa. The review will start by outlining the key anatomical structures of the equine central nervous system that are relevant to behavioural output.
Section snippets
Equine central nervous system relevant to behavioural output
In order to behave appropriately within a shifting environment, the horse’s brain must gather information from sensory receptors such as the retinae and epithelial somatosensory receptors, and convey these via the sensory branches of the peripheral nervous system (PNS) to the spine and then the brain. Following a process of integration, influenced by a combination of genomic, genetic and epigenetic processes as well as prior experience (learning), an appropriate behavioural response is issued
Learning and motivation
Operant learning theory is partitioned into positive reinforcement, negative reinforcement and punishment. Reinforcement is the strengthening of a behavioural response to a discriminative stimulus [cue] either through the introduction of an appetitive stimulus [positive reinforcement] or the removal of an aversive stimulus [negative reinforcement] as a consequence of the animal's response. Conversely, punishment is the weakening of a behavioural response to a discriminative stimulus by the
Predictive markers of the neurophysiological and behavioural phenotype
The term endophenotype describes the categorisation of an animal's behavioural traits in relation to its genetic profile (John and Lewis, 1965). It describes the predisposition to express specific categories of normal and abnormal behaviour as a result of the genotype-environment interaction. For example, the trait of ‘mood instability’ is considered to be an endophenotype for attention deficit hyperactivity disorder (ADHD) in relation to specific polymorphic markers within the dopamine
Conclusions and areas for future research
Understanding the mechanisms underpinning behaviour brings additional understanding about the behaviour itself. In particular, it provides a better awareness of how factors can affect behaviour, from the interaction of genes and environment, through to specific events such as the application of an aversive stimulus. Practically, this allows further optimisation of training techniques and the opportunity to improve the husbandry of the horse.
The neurotransmitter dopamine has featured heavily in
Conflict of interest statement
None.
Acknowledgements
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2021, Applied Animal Behaviour ScienceCitation Excerpt :Habituation occurs where repeated exposure decreases response without sensory or motor fatigue (Rankin et al., 2009). Habituation plays an important role in the learning component of training horses (McBride et al., 2017), and older horses have been shown to be less behaviourally responsive due to changes in physiology and emotional expression in response to stimuli (Baragli et al., 2014). Other studies evaluating experience in relation to reactivity to tasks reported that horses were more accepting of tasks and showed more positive, calm behaviours in a second exposure to tasks after the use of what were deemed as positive training methods (Furiex et al., 2009; Heleski and Bello, 2010; Sankey et al., 2010).